There are now five American women in the third round, the most since 2006 in Paris.

While the two younger players were both quite impressive in their victories, it was Mattek-Sands’ performance out of Roland Garros’ Court 1, the famed Bull Ring, that raised the most eyebrows. The 28-year-old has been playing standout ball for much of this year but had never notched a win as significant as beating Li at a major.

Mattek-Sands upset Marion Bartoli back at 2008 Wimbledon the year after the Frenchwoman reached the final, but that was not quite as big as defeating a woman who had won the French title just two years ago, is ranked No. 6 and has been playing well for the most part since last summer.

"At a Grand Slam it's my biggest win," said Mattek-Sands, who raced out to 5-0 lead in the third set and then shut down a late charge from Li. "I'm really proud of myself I was able to close out the match the way I did. You always get excited towards the end. I was really happy with how I stayed calm and stuck with my system that I have going during the points."

Since Stephens took the tennis world by storm in January, when she upset Serena Williams at the Australian Open, and then stood toe to toe with eventual champion Victoria Azarenka before going down in three in the semis, she has struggled with her newfound fame. She sputtered during the U.S. hard-court swing this spring, compiling a 2-7 record until the tournament in Rome, where she was finally able to string two wins together before she went down to Maria Sharapova. Last week in Brussels, she picked up another two wins.

But in both those locales, the U.S. Fed Cupper didn’t play as cleanly and effectively as she did against King, as she raced about the court and tore the cover off the ball, ripping 29 winners. Stephens appeared to be unaffected by the rain breaks against King, but she is not that patient of a person and grew bored of waiting. She played with her phone, and took a nap, but that didn't help much.

"You literally have nothing to do," Stephens said. "Should I eat? Do cartwheels? You have no idea what to do so it's just kind of you're lost. But it is what it is."

The world No. 17 still isn’t as footloose and fancy free as she was Down Under, but she is growing in confidence again.

"I've been playing better and better," she said. "It's just always tough playing an American, so just to get out there I was a little nervous. But I've been playing well, so I was just excited to get out there. A lot of it is finding the balance. It's definitely been tough, but [I’m] definitely playing better again. Just happy to be competing and on the court and winning matches."